The cinema industry continues to become more competitive. In view of such competition, the trend is to automate as much of the sequencing of the cinematic presentation process as possible to reduce costs. The cinematic presentation includes a sound component and a visual component that are properly sequenced with respect to each other. With the emergence of digital projection and sound systems in theatres it has become easier to automate the cinematic presentation sequencing using computer-controlled show automation systems such that staff is not required to set-up the projector and sound system each time the presentation is run. Accordingly, the presentation quality (e.g. the sound and visual performance) may be monitored less frequently.
For organizations that take pride to ensure the theatre patron is provided the best show experience possible, quality problems can be an ongoing concern. In particular the sound quality problems associated with the degradation of the sound system can result in the sound not meeting the quality sound expected by the theatre patron and can reduce the experience of a premium presentation.
Cinema loudspeaker systems need to perform reliably for extended periods. This is in conflict with the natural changes in the loudspeaker characteristics due to aging or changing environmental conditions, such as temperature and humidity. These natural changes, among other changing performance characteristics, are a typical problem that occurs over time. Other potential performance issues include (i) one driver in a cluster of drivers within a loudspeaker fails or is experiencing a degradation because of a loose connection or otherwise; (ii) a fuse blows, leaving inoperable the mid-range driver(s) or high range driver(s); and (iii) audio amplifier degradation or failures to degraded sound in the theatre. One approach to recognize one or more of these deficiencies is to repeat a theatre sound system tuning test to determine a performance deficiency.
Additionally, the acoustics of the theatre hall can change depending on the number of viewing patrons present (i.e. acoustics can be different if the theatre is full than if the theatre is nearly empty) and the location within the hall of where the patrons are seated. If the acoustics of the hall has changed, causing a reduction in sound quality, adjustments to the equalization of the sound system may be required to compensate for the change.
Typically initial tuning of the sound system is performed during theatre sound system installations in which the performance of the sound system setup is measured and calibrated using a microphone. Measuring with the microphone is performed at various seat positions in the theatre to ensure the sound for most if not all seat locations are optimized. Unfortunately, the setup used for calibration does not lend itself to be used as a sound system monitoring setup. This is partially because patrons are in theatre seats during the monitoring (but not during tuning), which ultimately influences the ability of such a setup to be used effectively for monitoring loudspeaker performance. To effectively monitor the sound quality, a microphone is placed a distance away from theatre patrons but still within the sound dispersion profile. This limits locations for monitoring microphone placement. For example, placing a microphone ten feet above a seating patron's head position and outside of the projected image path may potentially place the microphone outside of the sound dispersion profile. Thus, the placement may not be an effective position for sound quality monitoring. Furthermore, temporarily lowering a microphone into position when the patrons are seated is an added element of complication that increases the expense of a monitoring system.
Alternatively, the performance of the loudspeakers can be evaluated during periodic inspections, but this process is time consuming and does not identify problems when the problems occur. For example, periodic inspection does not provide any remedy or compensation for changes in acoustical performance until service can be arranged. As with the installation calibration setup, trained personnel is needed to perform measurements properly in monitoring on a periodic basis, thus making this approach less attractive economically (among other reasons).
In addition, the acoustical effects of nearby surfaces can alter the acoustical transfer characteristics of the microphone significantly if the microphones are placed in sub-optimal (e.g. non-ideal) locations. If measurements are made from these locations without otherwise compensating for the complex interactions that occur (and assuming the measurement hardware has a flat response), the correction applied to the loudspeaker response may be distorted by the acoustics of the microphone location. Accordingly, sub-optimal microphone placement is generally avoided.
The acoustical interaction may be too complex to approximate with a simple weighting filter unique to each microphone in each theatre. Discrepancies between the actual acoustical transfer function and an approximated weighting filter may be interpreted by the measurement system as an error to be corrected. This is undesirable as the loudspeaker response can be corrected to compensate for the microphone response rather than the opposite.
Accordingly, systems and methods for theatre sound quality monitoring are desirable that can be implemented using microphones placed in a variety of positions, including sub-optimal positions. Systems and methods are also desirable that can monitor for theatre sound quality effectively to compensate quality problems automatically. Systems and methods are also desirable that can identify larger issues with a theatre sound system and notify theatre operators regarding those larger issues.